Intelligent Laser Interlock System

ABSTRACT

The present invention comprises, in various embodiments, systems and methods for shutting down a laser system in an intelligent and flexible manner. An intelligent laser interlock system includes both hardwired components, and intelligent components configured to execute computing instructions. The hardwired components and the intelligent components are configured to shutdown the laser system to one or more alternative shutdown states in response to one or more interlock signals.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser.No. 60/796,646 entitled “Laser System Software Development Platform,”filed Apr. 26, 2006, which is hereby incorporated herein by reference.

BACKGROUND

1. Field of the Invention

The present invention relates in general to the fields of laser lightamplification and software control systems.

2. Related Art

Laser interlock systems are configured to ensure a laser systemoperator's safety and/or to protect one or more laser system componentsfrom damage. Laser interlock systems typically include electromechanicalsystems configured to shutdown a laser system when some operationallimit has been exceeded. For example, mechanical laser interlock systemsmay include mechanical relays connected to simple hardwired logiccircuits. The mechanical relays are configured to close a shutter or cutpower to one or more laser system components within the laser system,thereby shutting down the laser system. For example, a laser interlocksystem may be configured to activate a mechanical relay configured todisable laser light generation when a system cover is opened.

The simple approach of prior laser interlock systems causes a totalshutdown of the laser system. While ensuring safety, the total shutdownhas a number of drawbacks. For example, the laser system may need to bewarmed up and calibrated again after a total shutdown before the lasersystem is again operational. There is, therefore, a need forimprovements in laser interlock systems.

SUMMARY

The present invention comprises, in various embodiments, systems andmethods for shutting down a laser system in an intelligent and flexiblemanner. An intelligent laser interlock system includes a first modulecomprising hardwired components, and a second module comprisingintelligent components configured to execute computing instructions. Thehardwired components and the intelligent components are configured toshutdown the laser system to one or more alternative shutdown states inresponse to one or more interlock signals. These alternative shutdownstates include intermediate shutdown states in which parts but not allof the laser system are shutdown.

Various embodiments of the invention include a system comprising anoscillator configured to generate a laser light pulse, an amplifierconfigured to receive the laser light pulse from the oscillator andamplify the laser light pulse, and a control system comprising an inputconfigured to receive an interlock signal, an integrated circuitconfigured to select a shutdown state from a plurality of alternativeshutdown states based on the interlock signal, and an output configuredto place the system in the selected shutdown state.

Various embodiments of the invention include a system comprising a lightsource configured to generate a laser light pulse, and a control systemcomprising a hardwired interlock module configured to shutdown a firstpart of the light source, and an intelligent interlock module configuredto shutdown a second part of the light source by executing computinginstructions.

Various embodiments of the invention include a method comprisingreceiving an interlock signal, shutting down a laser system to a firstshutdown state responsive to the interlock signal, the first shutdownstate being an intermediate shutdown state, analyzing the interlocksignal, and shutting down the laser system to a second shutdown statebased on the analysis of the interlock signal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a laser system, according to various embodiments ofthe invention;

FIG. 2 is a block diagram that illustrates an intelligent laserinterlock system, according to various embodiments of the invention;

FIG. 3 illustrates methods of using the intelligent laser interlocksystem illustrated in FIG. 2, according to various embodiments of theinvention; and

FIG. 4 illustrates methods of shutting down the laser system of FIG. 1,according to various embodiments of the invention.

DETAILED DESCRIPTION

In some embodiments of the present invention, an intelligent laserinterlock system is configured to shutdown a laser system to one or morealternative shutdown states in an intelligent manner. The laser systemtypically includes multiple components, such as an optical oscillatorconfigured to generate a laser light pulse and an optical amplifierconfigured to amplify the laser light pulse. The alternative shutdownstates may include one or more partial shutdown states in which some butnot all of the multiple laser system components are shutdown. Forexample, in some embodiments, one of the one or more intermediate (e.g.,partial) shutdown states includes shutting down an optical amplifier butnot shutting down an optical oscillator. In some embodiments,establishing a shutdown state includes shutting down one or morecomponents external to the laser system.

In some embodiments, the intelligent laser interlock system isconfigured to be programmed by an end user or a developer to specify oneor more system shutdown processes. The developer can be a vendor, areseller, an original equipment manufacturer, a systems integrator, anengineer, or an entity that provides the intelligent laser interlocksystem to the end user. The one or more system shutdown processesinclude a shutdown sequence specifying an order in which laser systemcomponents are to be shutdown and including a shutdown timing specifyinga time at which each of the one or more laser system components are tobe shutdown in relation to one another. Each of the one or more systemshutdown processes is configured to place the laser system into one ofthe plurality of shutdown states.

In various embodiments, the intelligent laser interlock system isconfigured to shut down the one or more laser system components in ashutdown sequence starting with one or more downstream components andending with one or more upstream components. Upstream and downstream aredefined with respect to the direction of propagation of the laser beam.For example, those laser system components that are configured toinitially generate a laser light pulse are considered to be upstreamrelative to those components that amplify the generated laser lightpulse.

The intelligent laser interlock system includes a hardwired interlockmodule whose functionality is determined by hardwired electricalconnections and optionally simple logic gates. Functionality of thehardwired components is typically fixed and not configurable withoutrewiring or physically changing circuits. The hardwired interlock moduleis configured to respond to one or more hardwired interlock triggers byactivating relays, shutters, and/or the like. For example, a hardwiredinterlock trigger may be activated by opening of a system cover. Thehardwired interlock module may respond to this hardwired interlocktrigger by closing a shutter such that a user is not exposed to laserlight.

The intelligent laser interlock system further includes an intelligentinterlock module whose functionality is determined by computinginstructions. The intelligent interlock module is typically configuredto respond to one or more intelligent interlock triggers by executingthese computing instructions. The computing instructions may beconfigured to sequentially shut down components of the laser system in aprescribed order, to shut down the laser system to an intermediateshutdown state responsive to an analysis of the intelligent interlocktrigger, to enable and disable various control signals, to operaterelays, to operate shutters, and/or the like.

In some embodiments, the intelligent interlock module is configured tobe programmed in order to customize a system shutdown process. Forexample, a user may program the system shutdown process via an externalcomputer system, a software program, or a laser system control panel.Alternatively, a vendor may program the system shutdown process via anexternal computer system, an Application Specific Integrated Circuit(ASIC), a Field Programmable Gate Array (FPGA), a microprocessor,software, or firmware. The computing instructions that the intelligentinterlock module is configured to execute may be embodied in firmware,hardware, or software stored on a computer readable medium. Theintelligent interlock module may comprise a microprocessor, anintegrated circuit, a Field Programmable Gate Array, a programmablelogic device, or the like. The intelligent interlock module may also beconfigured to connect to an external computer system.

An intelligent interlock trigger may be configured to be activated ifthe temperature of an optical amplifier exceeds a predeterminedthreshold. In response to this intelligent interlock trigger, theintelligent interlock module may cause a partial shutdown of the opticalamplifier module such that the optical amplifier module can cool. Thispartial shutdown of the optical amplifier may not require shutdown ofother system components of the laser system. The intelligent interlockmodule enables minor anomalous situations requiring a partial shutdownto be efficiently handled while maintaining an operational readinessstate in the rest of the laser system.

FIG. 1 illustrates various embodiments of a laser system generallydesignated 100 and configured to generate a laser beam output 102 usingan amplifier 104 and an oscillator 106 under the control of a controlsystem 108. This control includes causing the oscillator 106 andamplifier 104 to generate the laser beam output according to a user'sneeds as well as managing the intelligent interlock system. The controlsystem 108, the oscillator 106, and the amplifier 104 are typically eachelectrically connected to one another and are optionally included withina single enclosure. For example, there are electrical connectionsbetween oscillator 106 and amplifier 104 that are not shown in FIG. 1.

The control system 108 comprises a plurality of components includingcontrol logic 112, optional user inputs 110, an optional externalcontrol interface 132, an optional display 116, and optional storage114. In some embodiments, the control system 108 includes aself-contained computer system, such as a standard commerciallyavailable single board computer. Typically, the control system 108 isconfigured to run a real time operating system along with a lasercontrol software application. In other embodiments, the control system108 is based on an embedded microcomputer or microcontroller and runs alaser control program. In still other embodiments, the control system108 is based on an Application Specific Integrated Circuit (ASIC) or aprogrammed Field Programmable Gate Array (FPGA).

User inputs 110 include controls configured for a user to operate thelaser system 100. These controls may be manual or electronic. Forexample, user inputs 110 may include a keyboard, one or more buttons, atouch screen, a dial, switches, and/or the like. The user inputs 110 areconfigured for turning a laser beam on, turning the laser beam off,selecting one or more characteristics of the laser beam, and the like.

The display 116 is typically a liquid crystal or light emitting diodedisplay. In various embodiments, the display 116 is configured todisplay system states, e.g., shutdown states, of the laser system 100 toa user. The system states may include, for example, informationregarding repetition rate, component temperature, pulse width, pulseenergy, or the like. Shutdown states may also include a list ofcomponents that are shutdown, a list of components that are notshutdown, why components were shutdown, a list of interlock triggers, orthe like.

External control interface 132 is configured to communicate commandsand/or data to or from one or more systems external to laser system 100.For example, external control interface 132 may be configured tocommunicate with a robot, an external trigger, a remote control, or anexternal interlock. In some embodiments, external control interface 132is configured to communicate using a network protocol, such as TCP/IP.In various embodiments, the external control interface 132 includes ahardwired connection such as a single wire, a pair of wires, a USBinterface, an Ethernet network interface, a FireWire interface, anRS-232 interface, a GPIB interface, or the like. Alternatively, theexternal control interface 132 includes a wireless connection such as aWiFi connection, a Bluetooth connection, a ZigBee connection, or thelike.

In various embodiments, the external control interface 132 is configuredto communicate one or more external interlock control inputs and/oroutputs. External interlock control inputs are configured for externalcontrol circuitry or external computer systems to activate theintelligent laser interlock system. For example, in some embodiments, afirst external interlock control input is configured to receive ahardwired interlock trigger and a second external interlock controlinput is configured to receive an intelligent interlock trigger. In someembodiments, external interlock control outputs are configured tocontrol external circuitry or computer systems in response to aninterlock trigger. For example, an external interlock control output maybe used to shutdown an external device in response to an intelligentinterlock trigger.

The storage 114 is configured to store operating parameters, logs ofevents that occur in the laser system 100, snapshots of system states ofthe laser system 100, and/or the like. For example, in some embodiments,the storage 114 is configured to store a snapshot of the state of lasersystem 100 at the time an interlock trigger is received. The storage 114may include volatile memory, non-volatile memory, a hard drive, anoptical drive, or the like.

The control logic 112 includes logic configured to execute computinginstructions. For example, control logic 112 may include a processor, anapplication specific integrated circuit, a field programmable gatearray, or the like. As is described further herein, the computinginstructions executed by the control logic 112 include those used torespond to intelligent interlock triggers. The control logic 112 alsoincludes wiring, comparators, logic gates (e.g., simple NAND, OR, andAND gates), and the like configured to perform hardwired operations.These hardwired operations include those used to respond to hardwiredinterlock triggers.

The oscillator 106 comprises oscillator logic 122, oscillatorelectronics 126, oscillator optics 130, and an optional oscillatorshutter 136. The control system 108 is configured to communicate withoscillator 106 through one or more connections 120. This communicationmay include the transmission of control signals and/or commands to theoscillator logic 122, and may include receipt of status information,such as temperature, beam characteristics, beam alignment, errorconditions, and interlock triggers from oscillator electronics 126.

The oscillator logic 122 comprises circuitry configured to control andmonitor the oscillator 106. For example, in various embodiments, theoscillator logic 122 receives a plurality of command and control datasignals from the control system 108 via connections 120 and, in turn,generates appropriate signals to control the oscillator electronics 126.In addition, the oscillator logic 122 typically includes circuitryconfigured to monitor one or more components of oscillator 106, andprovide appropriate signals back to the control system 108 viaconnections 120. These signals may include interlock triggers and/ordata indicative of a state of the oscillator 106. Oscillator logic 122is coupled to oscillator electronics 126 via connections 124.

The oscillator electronics 126 are configured to supply power to theoscillator optics 130, and may include for example power amplifiers,trigger signals, heater power supplies, laser diode inputs, and/or thelike. The oscillator electronics 126 are also configured to generatesignals representative of states of oscillator 106. For example, theoscillator electronics 126 may include a temperature sensor andtransducer, a flow sensor, a photodetector, a position sensor, and/orthe like. The oscillator electronics 126 are optionally configured tocontrol the oscillator shutter 136. The oscillator electronics 126 arecoupled to the oscillator optics 130 and the oscillator shutter 136 viaconnections 128.

The oscillator optics 130 are configured to generate light pulses. Theselaser light pulses may be characterized by a laser light pulse power, atemporal width, a repetition rate, and a wavelength distribution. Thepulse power may be defined as an average optical power present in thelaser beam per unit time, or a peak power present in a single lightpulse. In some embodiments, the light pulses generated by the oscillatoroptics 130 are chirped light pulses. The oscillator optics 130 mayinclude a ring laser, an optical oscillator, a Bragg fiber, a pulsestretcher, a fiber optic, an optical pump source, an optical switch,and/or the like.

The oscillator shutter 136 is configured to block optical path 134 suchthat light pulses generated by the oscillator optics 130 are preventedfrom reaching the amplifier 104. The oscillator shutter 136 may includea mechanical shutter or an optical switch.

The amplifier 104 is configured to amplify optical pulses received fromthe oscillator 106 via the optical path 134. Amplifier 104 comprises anamplifier logic 138, an amplifier electronics 142, an amplifier optics146, an optional external interface 162, and an optional amplifiershutter 148. The control system 108 is configured to communicate dataand/or commands to the amplifier logic 138 through connections 118, andis further configured to receive data such as status and errorconditions from the amplifier logic 138 through the amplifierconnections 118.

The amplifier logic 138 comprises circuitry configured to control andmonitor the amplifier 104. For example, in various embodiments, theamplifier logic 138 receives a plurality of command and control datasignals from the control system 108 via connections 118 and, in turn,generates appropriate signals to control the amplifier electronics 142.In addition, the amplifier logic 138 typically includes circuitryconfigured to monitor one or more components of amplifier 104, andprovide appropriate signals back to the control system 108 viaconnections 118. These signals may include interlock triggers and/ordata indicative of a state of amplifier 104. The amplifier logic 138 iscoupled to the amplifier electronics 142 via connections 140.

The amplifier electronics 142 are configured to supply power toamplifier optics 146, and may include for example power amplifiers,trigger signals, heater power supplies, laser diode inputs, and/or thelike. Amplifier electronics 142 are also configured to generate signalsrepresentative of states of amplifier 104. For example, amplifierelectronics 142 may include a temperature sensor and transducer, aphotodetector, a position sensor, and/or the like. Amplifier electronics142 are optionally configured to control amplifier shutter 148.Amplifier electronics 142 are coupled to amplifier optics 146 andamplifier shutter 148 via connections 144.

The amplifier optics 146 are configured to amplify light pulses receivedfrom oscillator optics 130. In some embodiments, the light pulsesgenerated by oscillator optics 130 are chirped light pulses andamplifier optics 146 includes optics, such as a Bragg fiber, configuredto temporally compress the amplified pulse. The amplifier optics 146 mayinclude fiber optics, free space optics, a thin film amplifier and/or afiber amplifier. In various embodiments, the amplified pulse is lessthan 1 nanosecond, 3 picoseconds, or 900 femtoseconds in width. Theamplified pulse is provided as laser beam output 102.

Amplifier shutter 148 is configured to block the laser beam output 102such that light pulses amplified by amplifier optics 146 do not leavelaser system 100. Amplifier shutter 148 may include a mechanical shutteror an optical switch.

In various embodiments, the amplifier 104 is configured to communicatewith one or more external systems via the external interface 150. Theseexternal systems may include an external interlock, a robot, an externaltrigger, a remote control, or an external interlock. In variousembodiments, the external interface 150 is configured to communicate oneor more external interlock control inputs and/or outputs. For example,external interface 150 may be used to communicate a signal fromintelligent interlock logic 290 to shutdown an external device, or mayreceive an intelligent interlock trigger from an external device.

In various embodiments, operation of the laser system 100 is subject toan intelligent interlock system. In some embodiments, the intelligentinterlock system is configured to separately shut down oscillator 106and amplifier 104 in response to hardwired and/or intelligent interlocktriggers.

FIG. 2 is a block diagram of an intelligent laser interlock systemgenerally designated 200, according to various embodiments of theinvention. The intelligent laser interlock system 200 comprises ahardwired interlock module 210 and an intelligent interlock module 220.As is described further herein, components of the intelligent interlocksystem 200 may be distributed among the control system 108, theoscillator 106 and the amplifier 104. Typically, the hardwired interlockmodule 210 is configured to respond to conditions that require immediateand/or invariant response. For example, the hardwired interlock module210 may be configured to respond to opening of a system cover by closingamplifier shutter 148 (FIG. 1). In some embodiments, it is desirablethat this response be as quick as possible.

Relative to the hardwired interlock module 210, the intelligentinterlock module 220 is typically configured to respond to conditionsthat require less immediate and/or more variant response. For example,the intelligent interlock module 220 may adjust the electrical powerprovided by amplifier electronics 142 or a laser pulse repetition ratein response to a temperature measurement.

As is described further herein, in some embodiments, both the hardwiredinterlock module 210 and the intelligent interlock module 220 are usedto respond to the same condition. For example, if the system cover isopened the hardwired interlock module 210 may close the amplifiershutter 148 and the intelligent interlock module 220 may turn off highvoltage circuits.

The hardwired interlock module 210 and intelligent interlock module 220are each responsive to sensors 230. Sensors 230 are configured to detecta condition of laser system 100 such as a temperature, voltage level,coolant flow, position, light pulse characteristic, and/or the like. Forexample, in various embodiments, sensors 230 include a thermocouple, ananalog to digital converter, a flow meter, position sensors, andphotodiodes. Sensors 230 are configured to generate an electricalsignal, such as a hi-low (e.g, TTL) logic signal, an analog signal, or amulti-bit digital signal. Some of sensors 230 may be dedicated tosending the generated electrical signal to hardwired interlock module210, some of sensors 230 may be dedicated to sending the generatedelectrical signal to intelligent interlock module 220, and some ofsensors 230 may send electrical signals to both interlock modules.Sensors 230 may be included in any part of laser system 100.

The hardwired interlock module 210 and intelligent interlock module 220are both configured to control shutdown activators 260. The shutdownactivators 260 may include relays configured to break electricalconnections, enable/disable signals, analog signals, switchers,mechanical shutters and/or positioners, warning messages, and/or thelike. The shutdown activators 260 may also include system controlelements such as parts of oscillator logic 122 or amplifier logic 138configured to control pulse repetition rates or output powers. Forexample, intelligent interlock module 220 may be configured to respondto a measured temperature by changing a pulse repetition rate.

The hardwired interlock module 210 includes an optional hardwiredtrigger logic 240 and a hardwired interlock logic 250. The hardwiredtrigger logic 240 is configured to receive an output of sensors 230 anddetermine if the output represents a state that requires generation of ahardwired interlock trigger. A hardwired interlock trigger is typicallya binary signal (e.g., a hi-low signal) that indicates that an interlockshould be activated. The hardwired trigger logic 240 may include simplelogic gates, comparators, analog-to-digital converters, and/or the like.For example, in some embodiments, the hardwired trigger logic 240 isconfigured to receive an analog signal from a member of sensors 230 andto compare this signal to a threshold voltage provided by a hardwiredlimits 245. A hardwired interlock trigger may then be generated inresponse to this comparison. In another example, the outputs of severalof sensors 230 may be processed through simple logic gates, to generatea hardwired interlock trigger.

Hardwired interlock triggers generated by the hardwired trigger logic240 are provided to hardwired interlock logic 250. The hardwired triggerlogic 240 is optionally in embodiments wherein the output of one ofsensors 230 is communicated directly to hardwired interlock logic 250.For example, if sensors 230 generate a binary signal, then this signalmay be used directly by hardwired interlock logic 250.

The hardwired interlock logic 250 is typically configured to receive avariety of different hardwired interlock triggers from hardwired triggerlogic 240. For example, hardwired interlock logic 250 may be configuredto receive different hardwired interlock triggers corresponding todifferent members of sensors 230. Hardwired interlock logic 250 includescircuits configured for controlling which of shutdown activators 260 areactivated by different hardwired trigger logic 240. These circuitsoptionally include NAND gates, AND gates, OR gates, and/or the like. Insome embodiments, hardwired interlock logic 250 includes a directconnection between hardwired trigger logic 240 or sensors 230 and amember of shutdown activators 260.

The communication of hardwired interlock triggers between hardwiredtrigger logic 240 and hardwired interlock logic 250 may be serial orparallel. In some embodiments, particular hardwired interlock triggersare identified by the electrical connection through which they arereceived. In some embodiments, there is a separate electrical connectorbetween hardwired trigger logic 240 and hardwired interlock logic 250for each possible hardwired interlock trigger.

The hardwired interlock logic 250 is optionally further configured tocommunicate signals to an intelligent interlock logic 290 included inintelligent interlock module 220. These signals are discussed furtherelsewhere herein.

In addition to intelligent interlock logic 290, intelligent interlockmodule 220 includes intelligent trigger logic 280. Intelligent triggerlogic 280 is configured to receive signals from sensors 230 anddetermine if an intelligent interlock trigger should be generated. Insome embodiments, the intelligent trigger logic 280 includes the sameelements and features as the hardwired trigger logic 240. However,intelligent trigger logic 280 may further include a limits memory 285configured to store electronically programmable thresholds. Theseelectronically programmable thresholds may be configured by writing datato the intelligent trigger logic 280. For example, in some embodiments,the electronically programmable thresholds can be configured by enteringdata through the user inputs 110 or through external control interface132.

In some embodiments, hardwired interlock module 210 includes directelectrical connections that connect the output of sensors 230 toshutdown activators 260. These direct electrical connections may beconfigured to communicate a response as quickly as possible.

The intelligent trigger logic 280 is configured to compare data storedin limits memory 285 with signals received from sensors 230 in order todetermine whether or not an intelligent interlock trigger should begenerated. The signals received from sensors 230 are optionallydigitized prior to this comparison. An intelligent interlock trigger isa signal that indicates that an interlock should be activated. Theintelligent interlock trigger may be a binary signal or a set of binarysignals (e.g. a sit of bits). For example, the intelligent interlocktrigger may include one, two or more bytes of data. In one embodiment,the intelligent interlock trigger includes a first byte indicating theidentity of the member of sensors 230 whose signal caused theintelligent interlock trigger. Additional bytes may include quantitativeinformation regarding the signal. For example, a second byte mayindicate how far a sensed temperature is above a temperature threshold.In some embodiments, intelligent trigger logic 280 is configured tocompare received sensor signals with calculated values, such as acalculated calibration value. Some limits may be determined duringoperation of laser system 100. For example, minimum and maximum pulseenergies may be entered by a user.

The intelligent interlock trigger generated by intelligent trigger logic280 is received by intelligent interlock logic 290. Intelligentinterlock logic 290 is configured to respond to the intelligentinterlock trigger by executing computing instructions. These computinginstructions may be embodied in hardware, firmware, or software storedon a computer readable medium. These computing instructions are alsooptionally reconfigurable. As such, the operation of intelligentinterlock logic 290 can be customized. Intelligent interlock logic 290optionally includes a processor and memory configured to execute andstore computing instructions, respectively.

Because intelligent interlock logic 290 is capable of executingcomputing instructions, intelligent interlock logic 290 can respond tointelligent interlock triggers with operations that include conditionalstatements (e.g., IF, WHILE, UNTIL, CASE, etc.) and these statements maybe dependent on comparisons (e.g., A>B, A=B, A≠B, etc.). Using theseoperations, intelligent interlock logic 290 may be configured to respondto an intelligent interlock trigger as a function of a state of thelaser system 100. For example, intelligent interlock logic 290 mayrespond differently to a detected high temperature depending on acurrent laser pulse repetition rate.

In some embodiments, different responses to an intelligent interlocktrigger are enabled as the laser system 100 is brought through aself-test and through a warm-up period. For example, during warm-up,temperatures, electrical conditions and optical parameters may beexpected to drift by a greater amount than when the laser system 100 isfully warmed up. Thus, intelligent trigger logic 280 may be configuredto use wider limits during the warm-up period and narrower limitsfollowing the warm-up period.

In some embodiments, limits used by intelligent trigger logic 280 aredependent on the state of laser system 100. For example, in a continuouspulses mode where pulses are produced nearly continuously at a highrepetition rate (e.g., >500 kHz) the average power detected at anoptical output sensor would be expected to be nearly constant.Therefore, limits related to an output power are applicable tomonitoring system performance. However, in a triggered mode in which onepulse is generated in response to one trigger event, the laser system100 may be on while there are longer periods between pulses. Duringthese periods, observation of the output power is not indicative of thesystem performance and limits related to the output power would not beused.

Intelligent interlock logic 290 is optionally further configured tooperate shutdown activators 260 so as to shut down laser system 100 toone or more intermediate shutdown states. By bringing laser system 100to an intermediate shutdown state, rather than completely shutting downlaser system 100, it may be possible to restore laser system 100 to afully operational state more quickly. Intelligent interlock logic 290 isoptionally configured to shut down parts of laser system 100 in avariety of alternative orders.

In some embodiments, intelligent interlock logic 290 is configured toshutdown laser system 100 to an intermediate shutdown state in whichoscillator optics 130 are being used to generate laser pulses butamplifier optics 146 are not provided with power to amplify thegenerated laser pulses. In some embodiments, intelligent interlock logic290 is configured to shut down dangerous parts (e.g., high voltages andhigh power pulse sources) of the laser system 100 in a first shutdownstate, and to shut down safe (e.g., low power) parts of the laser system100 in a second shutdown state.

In some embodiments, hardwired interlock module 210 is configured toshutdown laser system 100 from a fully operation state to a firstintermediate shutdown state, and intelligent interlock module 220 isconfigured to determine whether or not laser system 100 should beshutdown from the first intermediate shutdown state to a second shutdownstate or to a fully shutdown state. For example, in response to a signalfrom sensors 230, hardwired interlock module 210 may shutdown operationof amplifier 104 and send an interlock trigger from hardwired interlocklogic 250 to intelligent interlock logic 290. The shutdown of amplifier104 is an example of an intermediate shutdown state and is facilitatedby the relatively rapid response of hardwired interlock module 210.Intelligent interlock module 220 is configured to respond to theinterlock trigger received from hardwired interlock module 210 byidentifying a state of laser system 100. This state may includeoperational characteristics of oscillator 106 as well as informationindicating that the operation of amplifier 104 is already shutdown.Based on the received interlock trigger and the determined state,intelligent interlock logic 290 may then determine if the generation oflaser pulses using oscillator optics 130 should be shutdown, or ifamplifier 104 can be restarted without first shutting down amplifier104.

In some embodiments, intelligent interlock system 200 is considered tostore one or more snapshots of the state of laser system 100. Thesesnapshots may reflect states of laser system 100 before, during, and/orafter receipt of an interlock trigger. For example, in some embodiments,control system 108 is configured to periodically store a state of lasersystem 100 in Storage 114. This state may be updated, for example, every0.5 or 1.0 seconds. When intelligent interlock trigger or hardwiredinterlock trigger is generated, control system 108 is configured topreserve (e.g., save) the stored state such that the stored state can beused for later analysis. In some embodiments, control system 108 isconfigured to store a state of laser system 100 while in an intermediateshutdown state. For example, laser system 100 may be changed from afully operational state to a first intermediate state by shutting downall or part of amplifier 104. In the first intermediate state, a stateof laser system 100 may be saved for later use, and then the lasersystem 100 may be shutdown from the first intermediate state to a secondintermediate shutdown state. Another state of the laser system 100 isoptionally saved at the second intermediate shutdown state.

Saved states of laser system 100 are optionally included in event logsexported by control system 108. For example, control system 108 may beconfigured to include system states and events in a log. This log may beexported through external control interface 132. The events included inthe log may comprise, for example, activation and deactivation ofcomponents, a number and characteristics of laser pulses produced,interlock triggers, movement of alignment optics, and/or the like.

While hardwired interlock module 210 and intelligent interlock module220 are illustrated as separate modules in FIG. 2, in alternativeembodiments these modules may share components. For example, hardwiredtrigger logic 240 and intelligent trigger logic 280 may share circuits.

FIG. 3 illustrates methods of using intelligent interlock system 200,according to various embodiments. In these methods, the output of one ormore of sensors 230 is used to generate both a hardwired interlocktrigger and an intelligent interlock trigger. These two interlocktriggers are processed using hardwired interlock logic 250 andintelligent interlock logic 290, respectively. As a result of thisprocessing, laser system 100 is shut down to one or more differentshutdown states.

More specifically, in a receive sensor output step 310 an output ofsensors 230 is received by hardwired trigger logic 240. Typically, thisoutput is received through a high speed connection, such as a directwire. As is described elsewhere herein, the sensor output may include atemperature, a position, a flow, a characteristic of a laser pulse,and/or the like. The sensor output is optionally received by intelligenttrigger logic 280 at approximately the same time as hardwired triggerlogic 240.

In a generate hardwired trigger step 320, the received sensor output isused to generate a hardwired interlock trigger using hardwired triggerlogic 240. In some embodiments, generation of the hardwired interlocktrigger includes merely passing the received sensor signal to an outputof hardwired trigger logic 240. For example, if the sensor output is a0V to 5V signal generated by a system cover position sensor, then thissignal may be used directly as a hardwired interlock trigger. In someembodiments, generation of the hardwired interlock trigger includesdigitizing the received sensor signal, comparing the received sensorsignal with a threshold, and/or passing the received sensor signalthough simple logic gates. The generated hardwired interlock trigger ispassed to hardwired interlock logic 250.

In a process hardwired trigger step 330, the hardwired interlock triggerprovided to hardwired interlock logic 250 by hardwired trigger logic 240is processed in order to control an appropriate member of shutdownactivators 260. In some embodiments, a single hardwired interlocktrigger may result in activation of more than one of shutdown activators260. For example, one of shutdown activators 260 may be used to closeoscillator shutter 136 while another of shutdown activators 260 may beused to disable part of amplifier electronics 142.

In some embodiments, the processing performed by hardwired interlocklogic 250 in process hardwired trigger step 330 includes merely passinga received hardwired interlock trigger to an appropriate shutdownactivator. For example, the 0V to 5V output of a system cover positionsensor may be passed directly to a shutter control motor. In someembodiments, the hardwired interlock logic 250 is configured to activateseveral members of shutdown activators 260 in response to one hardwiredinterlock trigger. In some embodiments, the hardwired interlock 250 isconfigured to activate one of shutdown activators 260 in response to alogical combination of different hardwired interlock triggers.

Process hardwired trigger step 330 may also include communication of aninterlock trigger from hardwired interlock logic 250 to intelligentinterlock logic 290. This interlock trigger is treated as an intelligentinterlock trigger by intelligent interlock logic 290 as, for example, isfurther described below with respect to a step 360.

In a shutdown step 340, all or part of laser system 100 is shutdownusing one or more members of shutdown activators 260 in response tosignals received from hardwired interlock logic 250. In someembodiments, parts of laser system 100 are shut down in a sequence fromupstream components to downstream components. For example, amplifieroptics 146 may be shut down before oscillator electronics 126. In someembodiments, hardwired interlock module 210 is configured to place lasersystem 100 in an intermediate shutdown state in which parts of amplifier104 are shutdown while oscillator electronics 126 and/or oscillatoroptics 130 are still operational.

In an optional generate intelligent interlock trigger step 350 anintelligent interlock trigger is generated using intelligent triggerlogic 280 in response to receiving a signal from one of sensors 230.Generate intelligent interlock trigger step 350 may include comparisonof the received signal to a customizable threshold stored in limitsmemory 285. The generated intelligent interlock trigger may include amulti-bit data. Generate intelligent trigger step 350 is optionallyperformed in parallel with generate hardwired trigger step 320.

In a process intelligent trigger step 360, an intelligent interlocktrigger is processed using intelligent interlock logic 290. Theintelligent interlock trigger may be that generated in generateintelligent interlock trigger step 350 and/or an interlock triggerreceived from hardwired interlock logic in process hardwired triggerstep 330. Process intelligent trigger step 360 and/or generateintelligent trigger step 350 are optionally performed in parallel withprocess hardwired trigger step 330.

The intelligent interlock trigger is processed by executing computinginstructions. These computing instructions are optionally usercustomizable and may be configured to shutdown laser system 100 from afirst intermediate shutdown state to another intermediate shutdown stateor to a complete shutdown state. In some embodiments, these computinginstructions are configured to differentiate between different types ofintelligent interlock triggers and determine which intermediate shutdownstate the laser system 100 should be placed in based on a determinedtype.

In some embodiments, the computing instructions are configured toanalyze the intelligent interlock trigger and determine if the lasersystem 100 can be restored to a fully operational state from anintermediate shutdown state. In some embodiments, intelligent interlocklogic 290 is configured to determine that an external device should beshut down by sending signals through external control interface 132 orexternal interface 150. In some embodiments, the computing instructionsare configured to save one or more states of laser system 100 or sendlog information to an external device in response to an intelligentinterlock trigger.

In a shutdown step 370, the state of laser system 100 is changedaccording to the processing of process intelligent trigger step 360.This change may include bringing the laser system 100 from a fullyoperational state to an intermediate shutdown state, from a firstintermediate shutdown state to a second shutdown state, or from anintermediate shutdown to a complete shutdown state.

FIG. 4 illustrates methods of shutting down the laser system 100 into aplurality of shutdown states, according to various embodiments. In thesemethods, the system is placed in a first shutdown state in response to ahardwired interlock trigger and placed in a second shutdown state inresponse to an intelligent interlock trigger. One or more snapshots ofthe state of laser system 100 may also be saved in response to theinterlock triggers.

Specifically, in a receive hardwired trigger step 410 hardwiredinterlock logic 250 receives and processes a hardwired interlocktrigger. This interlock trigger is processed using hardwired logic as isdescribed elsewhere herein. The results of the processing may includesending one or more signals to shutdown activators 260, sending aninterlock trigger to intelligent interlock logic 290, saving a state oflaser system 100, sending log data to one or more external devices,and/or the like.

In a shutdown step 420, the state of laser system 100 is changed usingshutdown activators 260 in response to the processing of the hardwiredinterlock trigger in receive hardwired trigger step 410. This statechange may include shutting down parts of amplifier 104 and/or parts ofoscillator 106 in order to reach an intermediate shutdown state.

In a receive intelligent trigger step 430 an intelligent interlocktrigger is received and processed by intelligent interlock logic 290.Receive intelligent trigger step 430 is optionally performed in parallelwith receive hardwired trigger step 410 and/or shutdown step 420. Theintelligent interlock trigger may be received from hardwired interlocklogic 250 and/or intelligent trigger logic 280, or from an externaldevice via external interface 150.

The intelligent interlock trigger is processed by executing computinginstructions included within intelligent interlock logic 290. As isdescribed elsewhere herein, these computing instructions may be userconfigurable.

In a shutdown step 440, the state of laser system 100 is changed for asecond time based on the processing in receive intelligent trigger step430. The second change in state may be from a first intermediateshutdown state to a second intermediate shutdown state, from the firstintermediate shutdown state to a fully operational state, or from thefirst intermediate shutdown state to essentially completely shutdownstate (e.g., a state in which neither oscillator optics 130 noramplifier optics 146 are used to generate laser light.)

In an optional store snapshot step 450, one or more snapshots of statesof laser system 100 are saved. Store snapshot step 450 may be performedseveral times in the methods illustrated by FIG. 4. For example, storesnapshot step 450 may occur in response to receive hardwired triggerstep 410, in parallel with shutdown step 420, in response to receiveintelligent trigger step 430, in parallel with shutdown step 440, and/orafter the completion of shutdown step 440. The snapshot stored in storesnapshot step 450 may be a snapshot that was first saved prior toreceive hardwired trigger step 410 and is stored on a more permanentbasis in store snapshot step 450.

In an optional transmit snapshot step 460, the one or more snapshotsstored in step 450 are transmitted from laser system 100 to an externaldevice via external control interface 132. Transmit snapshot step 460may also include transmitting an event log to the external device.

Several embodiments are specifically illustrated and/or describedherein. However, it will be appreciated that modifications andvariations are covered by the above teachings and within the scope ofthe appended claims without departing from the spirit and intended scopethereof. For example, systems and methods of the invention may includemore than one of intelligent interlock module 200. One of intelligentinterlock module 200 may be used to control more than one amplifier 104.Some laser system components that are described as being disposed withinthe oscillator 106 may be disposed within the control system 108 orwithin the amplifier 104 while being configured to perform anessentially similar function. Some laser system components that aredescribed as being disposed within the amplifier 104 may be disposedwithin the control system 108 or within the oscillator 106 while beingconfigured to perform an essentially similar function. In someembodiments, signals from external control interface 132 and/or externalinterface 150 are used as inputs to hardwired trigger logic 240 and/orintelligent trigger logic 280, in addition to or as an alternative tosignals from sensors 230. The signals from external control interface132 and external interface 150 may be used to generate hardwiredinterlock triggers and/or intelligent interlock triggers, as describedelsewhere herein.

The embodiments discussed herein are illustrative of the presentinvention. As these embodiments of the present invention are describedwith reference to illustrations, various modifications or adaptations ofthe methods and or specific structures described may become apparent tothose skilled in the art. All such modifications, adaptations, orvariations that rely upon the teachings of the present invention, andthrough which these teachings have advanced the art, are considered tobe within the spirit and scope of the present invention. Hence, thesedescriptions and drawings should not be considered in a limiting sense,as it is understood that the present invention is in no way limited toonly the embodiments illustrated.

1. A system comprising: an oscillator configured to generate a laserlight pulse; an amplifier configured to receive the laser light pulsefrom the oscillator and amplify the laser light pulse; and a controlsystem comprising an input configured to receive an interlock signal, anintegrated circuit configured to select a shutdown state from aplurality of alternative shutdown states based on the interlock signal,and an output configured to place the system in the selected shutdownstate.
 2. The system of claim 1, wherein one shutdown state includesshutting down the amplifier but not the oscillator.
 3. The system ofclaim 1, wherein one shutdown state includes shutting down an externalcomponent.
 4. The system of claim 1, wherein the control system isconfigured to control a plurality of oscillators.
 5. The system of claim1, wherein the control system is configured to control a plurality ofamplifiers.
 6. The system of claim 1, wherein the control system isconfigured to store a snapshot of a system state.
 7. The system of claim1, wherein the control system is configured to communicate with anexternal computer system.
 8. The system of claim 1, wherein a durationof the laser light pulse is less than 1 nanosecond.
 9. The system ofclaim 1, wherein a duration of the laser light pulse is less than 3picoseconds.
 10. A system comprising: a light source configured togenerate a laser light pulse; and a control system comprising ahardwired interlock module configured to shutdown a first part of thelight source, and an intelligent interlock module configured to shutdowna second part of the light source by executing computing instructions.11. The system of claim 10 wherein the first part of the light source isan amplifier.
 12. The system of claim 10 wherein the intelligentinterlock module is programmable by the user.
 13. The system of claim 10wherein the intelligent interlock module and the hardwired interlockmodule are configured to operate in parallel.
 14. The system of claim 10wherein the hardwired interlock module includes at least one hardwiredinterlock trigger and at least one shutdown activator configured toshutdown at least one set of system components upon activation of thehardwired interlock trigger.
 15. The system of claim 10 wherein theintelligent interlock module includes at least one intelligent interlocktrigger comprising an integrated circuit, and at least one shutdownactivator, the at least one intelligent interlock trigger beingconfigured to activate at least one shutdown activator.
 16. The systemof claim 10 wherein the hardwired interlock module is configured to sendan interlock trigger to the intelligent interlock module.
 17. A methodcomprising: receiving an interlock signal; shutting down a laser systemto a first shutdown state responsive to the interlock signal, the firstshutdown state being an intermediate shutdown state; analyzing theinterlock signal; and shutting down the laser system to a secondshutdown state based on the analysis of the interlock signal.
 18. Themethod of claim 17, wherein shutting down the laser system comprisesshutting down one or more system components in a sequence from adownstream component to an upstream component.
 19. The method of claim17, further comprising storing a snapshot of a system state.
 20. Themethod of claim 17, wherein shutting down the laser system to the firstshutdown state includes halting the amplification of pulses, andshutting down the laser system to a second shutdown state includeshalting the generation of laser pulses.